By:
Dr. Jeff Masters,
7:10 PM GMT on May 16, 2009
The latest 00Z and 12Z runs of the GFS, UKMET, NOGAPS, and ECMWF global dynamical computer models continue to indicate the possibility of an early season subtropical storm forming in the Gulf of Mexico 3 - 7 days from now. A modest area of low shear air is expected to open up between the polar jet stream to the north and the subtropical jet stream to the south, between Cuba and the northern Gulf of Mexico. The models have not been consistent with the timing or the size of this low shear area, and I wouldn't be surprised to see them back off again from this forecast with Sunday's set of runs. Nevertheless, I'll call once again for a 10% chance of development of a subtropical depression in the eastern Gulf of Mexico, 4 - 7 days from now. There isn't much of a disturbance at present to look at--there are some scattered showers between Cuba and Jamaica, but they are under a hefty 30 knots of wind shear. These showers should gradually increase in intensity and areal coverage over the next two days, and
phase space diagrams from Florida State University indicate that an extratropical low may form near the western tip of Cuba 2 - 3 days from now. The storm may then gradually transition to a subtropical or tropical system later in the week, if the shear is low enough. Even if the shear is high and the storm remains extratropical, it could be a substantial rain-maker where it comes ashore. The models target the northern Gulf Coast between Louisiana and the Florida Panhandle as the most likely landfall location, but it is too early to place any confidence in this track.
There is also about a 10% chance a subtropical storm may form in the mid-Atlantic a few hundred miles east of Bermuda. There, a large upper-level cold low has cut off from the jet stream, and it may spin in place long enough over the next week to develop a warm core and be classified as a subtropical storm. It is unlikely that a subtropical storm forming that far out in the Atlantic this early in the year would pose a threat to any land areas, with the possible exception of Bermuda.
Climatology of early-season Atlantic tropical cyclonesTropical storms are uncommon in the Atlantic before June 1, with only 26 named storms on record between 1851 - 2008. Five of these have made it to hurricane strength, and only one--
Hurricane Able of 1951--made it to major hurricane status. Last year's
Tropical Storm Arthur may be the deadliest May tropical cyclone on record. Though only a 40 mph tropical storm at landfall, Arthur killed five people in Belize and caused $78 million in damage. Three early-season storms have brought hurricane-force winds to land. The
March 1908 hurricane swept through the northern Lesser Antilles Islands as a Category 1 or 2 hurricane, destroying at least 24 boats and causing damage to buildings on St. Bartholomew.
Hurricane Able of 1951
brought sustained winds of 90 - 95 mph to the northern Bahama Islands, but caused little damage.
Hurricane 2 of May 1908 hit North Carolina's Outer Banks as a Category 1 hurricane, but also caused little damage.
Figure 1. Tracking map for the earliest hurricane to make landfall, the March 1908 hurricane in the northern Lesser Antilles Islands.
List of all early season (formed in January - May) Atlantic named stormsMay 31, 2008:
Tropical Storm ArthurMay 6, 2007:
Subtropical Storm AndreaApril 18, 2003:
Tropical Storm AnaApril 21, 1992:
Subtropical Storm 1May 6, 1981:
Tropical Storm ArleneJanuary 18, 1978:
Subtropical Storm 1May 21, 1976:
Subtropical Storm 1May 23, 1972:
Subtropical Storm AlphaMay 17, 1970:
Hurricane Alma (Category 1)
May 28, 1959:
Tropical Storm ArleneFebruary 2, 1953:
Tropical Storm AliceMay 25, 1952:
Tropical Storm 1May 15, 1951:
Hurricane Able (Category 3)
May 22, 1948:
Tropical Storm 1May 19, 1940:
Tropical Storm 1May 27, 1934:
Tropical Storm 1May 14, 1933:
Tropical Storm 1May 5, 1932:
Tropical Storm 1May 13, 1916:
Tropical Storm 1May 24, 1908:
Hurricane 2 (Category 1)
March 6, 1908:
Hurricane 1 (Category 2)
May 27, 1890:
Tropical Storm 1May 16, 1889:
Hurricane 1 (Category 1)
May 17, 1887:
Tropical Storm 2May 15, 1887:
Tropical Storm 1May 30, 1865:
Tropical Storm 1I'll have an update Sunday.
Jeff Masters